Slow make and break switch



P. HUTT ET AL SLOW MAKE AND BREAK SWITCH Filed Aug. 30, 1954 Aug. 19,1958 2,848,574

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the narrow ledge 22. The resilient contact blade 32 then extends acrossthe central depression 20 with the free end 37 underlying the contactportion 27 of the fixed contact 25. Looking at Figure 5, it should beappreciated that the strut members 28 and 34 of contacts 25 and 30respectively are held down by the insulating cover member 18 so that thecontacts are fulcrumed on the ledges 22 and held in place by the notches23 in the end walls of the switch housing.

In order to furnish a more positive holding action for the contacts inthe housing, we have provided hold-down blocks 40 for preventing thecontacts from shifting out of position under conditions of roughhandling that might cause the contacts to drop. out of the housingthrough the openings 21. These blocks are best shown in Figure 9 andthey are dimensioned to fill up most of the space in the housing betweenthe struts 28 and 34 respectively and the adjacent end walls of thehousing while extending from one side wall to the other within thehousing. The central portion of the blocks 40 is cut out as at 41 inorder to accommodate the mounting screw (not shown) that is used tofasten the switch to a supporting surface by engaging in the threadedaperture 16 in the cover plate ll. Similar cut-outs 42 and 43 areprovided at either side of cut-out 41 to accommodate the shank of theterminal screws 17 as well as the upwardly extending tongue 33 of themovable contact 30.

As mentioned before, a pivoted trigger 15 is provided in the switchhousing for actuating the movable switch blades 32. Trunnions 45 areformed on the sides of the trigger to lie within open bearings 46 formedin the opposite side walls of the body 10. The cover plates 11 and 18overlie the trunnions 45 in the bearings 46 so that the trigger isconfined to rotational movement in the bearings. Between the trunnions4S, and at the lower end thereof, the trigger is provided with a roundedprojection 47 that is adapted to bear on the upper sur face of thecontact blades 32 of the movable contacts 3%). In the position of thetrigger 15 in Figure 5, the projection 7 is engaged within the concaveportion 36 of the blade 32. in this position the free end 37 of blade 32is in engagement with the fixed contact portion 27 in order to completethe circuit. Thus, if the trigger 15 were pivoted to the left, theprojection 4-7 would depress the blade 32 to open the circuit at thatpoint. Since the second set of contacts is oppositely arranged from thefirst set mentioned above, it should be appreciated that when thetrigger is moved the action of the one set of contacts will be oppositefrom the action of the remaining set so that this switch is in effect asinglepole double-throw switch.

A detent spring 50, as is best shown in Figures 4, and 7, is locatedcentrally within the depression 20 of the housing to underlie therounded projection 47 of the trigger 15. The function of this spring isto normally hold the trigger in either of its two extreme positions sothat more than a casual force is needed to move the trigger 15 to itsopposite position. This spring is made from a thin strip of resilientmaterial such as beryllium copper and it has an arched central portion51 as well as arched end portions 52 which are bifurcated to form a pairof downwardly extending legs 53 at both ends of the spring.Longitudinally spaced shelves 55 are formed adjacent the centraldepression 29 for supporting the spring 50 above the bottom wall ofdepression 20. Opposed abutments 56 are formed on the shelves 55 to bestraddled by the bifurcated ends 52 of the spring 50 so that the springis held in the housing by pressure against the opposite walls of thedepression as well as by the cooperation of the abutments 56 with thebifurcations 52. The bifurcated ends 52 of the spring are of graduallydiminishing cross-sectional area from the arched central portion to theends of the spring. Thus, the spring is of substantially uniformstrength. The spring is supported at both ends and the load is appliedover the arched central portion. Both the width and thickness of thespring material are uniform so that the cross-sectional area is amaximum at the arched central portion that is designated as the area ofloading. Hence, the outline of this spring in plan view is equivalent totwo triangles in opposed relation with their apexes at the area wherethe load is supported by the spring. See Figure 4. Accordingly, themovement of the trigger 15 is resisted by the spring pressure of thedetent spring 50 which must be overcome by depressing the arched portion51 of the spring until the rounded projection 47 of the trigger iscapable of riding over the arch 51 to operate the switch and make orbreak contact between the movable contacts 30 and the fixed contacts 25.

Consequently, having described our invention of a new and improved slowmake and break electric switch, it will be readily apparent to thoseskilled in this art that we have devised a switch which is simple indesign, reliable in operation and easy to assemble as well as readilyadaptable to mass production methods of manufacture. While we have shownhold-down blocks for use with the movable and fixed contacts, it shouldbe appreciated that under many conditions they may be eliminated as thecover plate may be relied upon to satisfactorily hold the contacts inthe housing. Under conditions of severe handling and usage, it ispreferable, however, to take advantage of the hold-down blocks so thatthe terminals are as reliable in operation as those which arepermanently fixed to the switch housing by means of rivets or the like.Also, this switch can very easily be made into a three-way switch bymerely placing a jumper strip across two adjacent terminals of theswitch. Also, one of the sets of contacts may be reversed so that themovable contacts will open and close simultaneously to form adouble-pole single-throw switch.

A possible modification of the detent spring would be to form the top ofthe arched central portion with a concavity so that the switch ischanged to a three position switch with a variety of circuitcombinations. As an example, the extreme end positions of the triggercould be the on positions for two different circuits while the middleposition would serve as the o position. This change in the design of thespring, and consequently the action of the switch, could be made withoutaltering the design of the other parts of the switch.

Modifications of this invention will occur to those skilled in this artand it is to be understood therefore that this invention is not limitedto the particular embodiment disclosed but that it is intended to coverall modifications which are within the true spirit and scope of thisinvention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electric switch comprising a recessed body member with a covermember for forming a hollow housing, the housing containing at least onefixed contact that is normally biased into engagement with a movablecontact, each contact having a terminal end to which a lead wire may beconnected, openings formed through the back Wall of said housing toaccommodate the terminals of said contacts, the said terminals lyingwithin the openings and being supported on a side ledge of theirrespective opening, upwardly inclined strut members formed on eachcontact to be in engagement with the underside of said cover so thateach terminal is held seated on said ledges by the downward forcesupplied by the cover while the opposite edge of each of the terminalsis held against an overlying stop member of the housing, and a triggerpivotally supported in said housing for holding the movable contact awayfrom the fixed contact.

2. An electric switch as recited in claim 1 wherein there are a pair offixed contacts and a pair of movable contacts normally biased intoengagement therewith, and a pair of hold-down blocks seated over anadjacent pair of the terminals of said contacts while also being inengagement with the underside of the cover to assist in fixedly securingthe terminals in the housing.

3. An electric switch comprising a hollow housing formed of a recessedbody member and a cover with a pair of fixed contacts that are normallybiased into engagement with a pair of movable contacts, openings formedthrough the back wall of said housing to accommodate the terminals ofsaid contacts, each of the said terminals lying within an opening andbeing fulcrumed on a side ledge of their respective openings, while theopposite edge of each of the terminals underlies a ledge of saidopenings, at hold-down block seated over the terminals and being forceddown by the cover to support the terminals in the openings, and atrigger pivotally supported in said base member for holding the movablecontact away from the fixed contact.

4. An electric switch comprising a hollow housing having a fixed contactin cooperation with a movable contact, each contact having a terminalend fixed in the housing to which a lead wire may be connected, and acover member for closing the said housing, a trigger pivotally mountedin the housing for moving the movable contact into and out of engagementwith the fixed contact, and a detent spring located in the path ofmovement of said trigger to hold the trigger in one of severalpredetermined positions, the spring having an arched central portion asWell as arched end portions, said arched end portions being bifurcatedalong their entire length and having substantially vertical legs forholding the central portion away from the supporting surface, the saidlegs of the spring being braced between opposed walls in the housingwith the legs at each end straddling an abutment formed as part of saidwalls so that the spring is supported against sidewise sliding movementin the housing.

5. An electric switch comprising a hollow housing, a

fixed contact and a movable contact blade located in the housing, amanually operated trigger pivotally mounted within the housing andengageable with the contact blade to move it away from the fixedcontact, the trigger having a handle portion that extends outwardlythrough a top opening in the housing, and a pair of opposed walls in thehousing, a detent spring braced between these opposed walls .and held inthe path of movement of the trigger to hold the trigger in one ofseveral predetermined positions, the spring having an arched centralportion and arched end portions which are turned down vertically at theends to form supporting legs, the spring being compressed slightlybetween the opposed walls to hold the spring in place, the said archedend portions being of gradually diminishing cross-sectional area frompoints adjacent the sides of the arched central portion to the nearestend of the spring.

6. An electric switch as recited in claim 5 wherein the said arched endportions are bifurcated to form a pair of vertical legs at both ends ofthe spring.

References Cited in the file of this patent UNITED STATES PATENTS1,153,505 Levison Sept. 14, 1915 1,878,667 Both Sept. 20, 1932 1,992,432Kilgour Feb. 26, 1935 2,253,968 Cook Aug. 26, 1941 2,377,134 DietrichMay 29, 1945 2,470,613 Gaynor May 17, 1949 2,500,181 Hubbell et al Mar.14, 1950 2,626,335 Landin Jan. 20, 1953 2,705,785 Benander Apr. 5, 1955FOREIGN PATENTS 110,450 Australia Apr. 23, 1940 562,631 Great BritainJuly 10, 1944

